Solar structure

ABSTRACT

A solar structure, and more particularly a greenhouse, comprising a framework formed from frame members (20, 20a) and a flexible cover (26) having portions (28) of varying optical density along its length, and wound between a pair of opposed spooled 24 mounted on respective sides of the framework such that the cover is wound from one spool to the opposed spool. The cover is constrained to move over rollers (22) extending longitudinally of the framework, and the edges of the cover are received to move within slots formed in the edges of the frame members.

TECHNICAL FIELD

The present invention relates to a dynamic membrane to regulate solarradiation and thus aid the environmental control of structures such asgreenhouses, swimming pools, patios, atriums and the like. A greenhouseis used as the example in this description.

BACKGROUND ART

Greenhouses are used to provide a sheltered, controlled environment forplant growth. Thus, most preferably, a greenhouse should foster plantlife within it by giving shelter, by controlling the reception of solarradiation, by providing controlled ventilation and by reducing nocturnalre-radiation.

It has been found in practice that all these aforementionedcharacteristics are difficult to achieve in concert in known greenhousestructures which have a fixed canopy or glazing; this is because thereception of required solar radiation by day is not compatible with theneed to conserve warmth by night.

Currently, in warm weather, gardeners whitewash or mount shade cloth tothe structure to reduce sunlight and cause vents to open or close toexhaust or trap air. In large greenhouse structures, fans are used forventilation and electro-mechanical rigid sliding roof panels have beenproposed. In cold periods warmth is achieved by heating, and insulatingmaterials may be added at night to prevent heat escape. These proceduresare imprecise, laborious and may consume excessive energy.

It is an object of the present invention to alleviate, at least in part,these aforementioned disadvantages.

DISCLOSURE OF THE INVENTION

According to the present invention there is provided a solar structurecomprising a framework defining a space there within, a flexible coverhaving a varying optical density along its length and forming a roof andat least part of a side wall for the structure, said cover being adaptedto be moved within said framework such that a selected portion of thecover overlies the space, and said cover solely forming the roof andsaid part of the side wall of the structure.

Preferably the cover is wound between a pair of opposed spools mountedon respective sides of the framework, whereby the cover is wound fromone spool to the opposed spool.

With the present invention, and in the case where the solar structureforms a greenhouse overlying a cultivating space, the internalenvironment of the greenhouse may be maintained or varied according tothe optical density of the framework cover selected to overlie thecultivating space. Thus, a particular choice of canopy length may bewound between the spools to form the canopy to match the particularambient weather conditions. For example, clear plastic may be the choicein dull conditions and shade cloth, e.g. 50% shade cloth, in brightsunlight or a combination of both may be selected where the materialsare juxtapositioned along the cover, whilst an insulating material maybe used to close up the greenhouse to conserve energy and contain heatat night, and to give protection during severe storms. These selectionsmay be manual, motorized or automatic, the automated processes beingoptionally controlled by a small computer programme and suitablesensors.

The ends of the greenhouse may be open or closed. When closed, a doormay be incorporated into one or both of the ends to permit entry to thecultivating space and the closed ends may be transparent, translucent oropaque, or a combination of these.

Preferably, the cover spools are disposed at the bottom of therespective sides of the framework and the cover forms the sole canopy ofthe greenhouse. Alternatively, the cover may form only a partialgreenhouse canopy. For example, the bottom portion of the framework onone or both sides may not be covered by the framework cover, with theopposed spools being remote from the bottom of the framework. Such aportion or portions may be covered by glazing or other structure, forexample, which may overcome problems with undulations in the ground atthe bottom of the framework or where the structure is connected toanother structure such as a house wall.

The framework cover may comprise a plurality of lengths of material,having different optical densities arranged sequentially along itslength. Each length is contiguous with adjacent lengths andadvantageously is capable of extending substantially fully from onespool to the opposed spool. One or more of the lengths of materialsparticularly an opaque length, may be heat insulating and/or heatreflective. One or more of the lengths of materials may be foraminous,such as in the form of shade cloth, with several foraminous lengthsadvantageously having holes of different size or different number toprovide regions of varying optical density and/or ventilation. Eachlength of material may take any suitable form, for example woven, orotherwise be formed as a continuous sheet and may be formed from anysuitable flexible materials such as polyethylene or PVC. The flexiblematerial may be suitably treated to possess a desired optical densityfor example by applying a coating or forming openings therethrough. Theflexible cover may be formed from a single length of material suitablyhaving a different optical density along its length.

The framework is conveniently gable shaped, alternatively, the frameworkmay adopt any other appropriate cross-section such as a triangular,rectangular, arched or bowed.

If the framework is longer than the optimum width of the frameworkcover, additional opposed spools and respective covers may be employedalong the framework. In such circumstances, cover lengths of differentoptical densities may overly the cultivating space along the length ofthe framework at any one time and may set up temperature gradientsand/or different conditions at different portions of the cultivatingspace as desired. This may be advantageous when different plants havingvarious requirements of temperature and sunlight are grown in the samegreenhouse.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention, in the form of a greenhouse,will now be described with reference to the accompanying drawings inwhich:

FIG. 1 is a perspective view of the greenhouse,

FIG. 2 is an enlarged view partly sectioned of circled region A of FIG.1,

FIG. 3 is an enlarged view partly sectioned of circled region B of FIG.1,

FIG. 4 is an enlarged view of the circled region C of FIG. 1, and

FIG. 5 is a schematic view showing the cover wound between opposedspools removed from the framework. Lengths of materials of differentoptical density are shown as discrete panels.

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIG. 1, the greenhouse comprises a framework 12 the roofforming part of which is of a gable like shape. The respective ends 14and 16 of the framework are filled in with glass or plastic which ispreferably transparent and double glazed. The end 16 has a door 18formed therein, to permit access to the cultivating space defined withinthe framework 12.

The framework 12 may be set on the ground, or on a prepared surface suchas a concrete slab or on rails such that the structure can be mobile.The framework 12 consists of a plurality of spaced upright members 20terminating at the ends of gable forming members 20a, four of which areshown in FIG. 1. The upright members 20 and the gable forming members20a are interconnected by five sets of cross members 22 disposedrespectively at the top, shoulder and bottom of both sides of themembers and extending longitudinally of the framework to give structuralintegrity to the framework. Each cross member 22 comprises a series ofrollers, with a single roller extending between adjacent frame members20, with the axis of rotation of the rollers 22 in each series being inalignment. A spool 24 is mounted for rotation at the base of respectiveupright members 20 and, as shown in FIG. 2, a series of aligned spools24 are supported for rotation, by the upright members 20.

Each spool 24 has wound thereon a flexible framework cover 26 havingvarying optical density along its length. The flexible cover passes froma spool 24 on one side of the framework 12 and over the framework to anopposed spool on the opposite side of the framework 12 as will behereinafter described.

FIG. 5 shows the cover 26 wound between opposed spools 24 but with theframework 12 removed for purposes of clarity only. The panels A, B and Crepresent adjacent lengths of material 28 having differing opticaldensities. Each length of material 28 is of sufficient length to spanthe framework 12 with the lengths A, B, and C being shown shortened forconvenience. The lengths 28 are arranged sequentially along the cover 26and are selected from transparent, translucent and opaque lengths. Someof the lengths may have heat insulating and/or heat reflectiveproperties and some of the lengths may be foraminous to provide shadeand ventilation. As shown in FIG. 5 the longitudinal ends 30 of adjacentlengths 28 are joined by a seam which may be stitched or welded.

The end positions of the framework cover are fixed to opposed spools 24using any convenient fixing arrangement, such as keying in to a slot ineach spool 24.

The framework cover 26 feeds from each spool 24 under the adjacentbottom cross member roller 22 which, together with the spools 24, areactually mounted for rotation between adjacent upright members 20 on thesame side of the framework, the position of the mounting being withinthe base of each member 20. The axes of rotation of the cross memberrollers 22 are parallel with the axes of rotation of the spools 24.

After passing under the bottom cross member roller 22, the edges of thecover 26 pass into guide means in the form of continuous slots 25 formedrespectively in the adjacent sides of the upright and gable members 20and 20a.

The edges of each side of the cover 26 are slidable along the slots 25of adjacent members 20 as the cover 26 is wound between the opposedspools, and, at the same time, the cover is maintained in asubstantially taut condition within the framework by the slots 25 and bythe cross member rollers 22. The cover may be wound between the opposedspools to select a particular length 28 of material according toexisting environmental conditions. For example, on very hot sunny days apartially transparent foraminous material such as a shade cloth may spanthe framework, creating shade and venting hot air to atmosphere. In coldconditions, the shade cloth may be wound from the framework 12 onto oneof the spools, and clear material wound across the framework 12 suchthat it spans the framework to cover the cultivating area so as to allowa maximum amount of radiation to enter the cultivating space. In warmconditions a combination of clear and foraminous material may span theframework 12 regulating the amount of radiation which can enter theenclosed area. In order to retain absorbed heat within the cultivatingspace, for example at night, an opaque insulating length may be woundfrom one of the spools to cover the framework. In cool conditions of lowangle sun a combination of clear and insulating material may span theframework where the radiation enters the space through the clearmaterial some striking the cultivation area and some reflected back ontothe cultivation area from the reflective inner surface of the insulatingmaterial. Such insulating lengths may, for example comprise metal coatedplastics.

The spools 24 may be rotated by motorised drive means (not shown)comprising, for example an electric motor, combustion engine or the likeconnected via a drive transmission to one or more of the spools 24thereby causing rotation in a desired sense of direction. Alternatively,a handle may be disposed at one or both ends of a spool 24 therebypermitting spool rotation. In the embodiment shown in FIG. 1, arotatable handle 21 may be positioned on both sides and either end ofthe framework 12 and in turn each carry a pulley forming part of apulley drive 21a to the respective spools 24. Thus the aligned spools 24may share a common drive shaft so that rotation of one of the spoolscauses each of the spools 24 along one side of the framework 12 torotate, followed by the spools 24 on the other side of the framework 12,pulled by the cover 26 through the slots 25 over the horizontal rollers22.

Sensing devices may be associated with the greenhouse to senseenvironment changes. Such sensing devices may be linked to amicroprocessor which activates winding of the spools 24 to causematerials 28 of a desired type to span the framework. The sensingdevice(s) may include a thermostat or light meter, which may be mountedfor example in the greenhouse interior.

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. It is to be understood that the inventionincludes all such variations and modifications which fall within itsspirit and scope.

I claim:
 1. A solar structure comprising:a framework defining a space therewithin, a flexible cover having a varying optical density along its length and forming at least part of a roof for the structure, said cover being adapted to be moved within said framework such that a selected portion of the cover overlies the space, and said cover solely forming the said at least part of the roof of the structure.
 2. A solar structure as claimed in claim 1, wherein the cover is wound between a pair of opposed spools mounted on respective sides of the framework, whereby the cover is wound from one spool to the opposed spool.
 3. A solar structure as defined in claim 2, wherein the flexible cover is also disposed over horizontal rollers extending along said framework.
 4. A solar structure as defined in claim 1, wherein the framework is slotted and the edges of the flexible cover are disposed within said slots.
 5. A solar structure as defined in claim 1, wherein the cover comprises materials with selected transparency and degrees of translucence and having insulating, reflecting and foraminous qualities, each of which materials may cover the internal space at any one time.
 6. A solar structure as defined in claim 1, wherein a combination of juxtapositioned materials may cove& the internal space at any one time.
 7. A solar structure according to claim 1, wherein the flexible cover also forms at least part of a sidewall for the structure, said cover solely forming the said part of the sidewall as well as the said at least part of said roof of the structure.
 8. A solar structure as claimed in claim 7, wherein the cover is wound between a pair of opposed spools mounted on respective sides of the framework, whereby the cover is wound from one spool to the opposed spool.
 9. A solar structure as defined in claim 8, wherein the flexible cover is also disposed over horizontal rollers extending along said framework.
 10. A solar structure as defined in claim 7, wherein the framework is slotted and the edges of the flexible cover are disposed within said slots.
 11. A solar structure as defined in claim 7, wherein the cover comprises materials with selected transparency and degrees of translucence and having insulating, reflecting and foraminous qualities, each of which materials may cover the internal space at any one time.
 12. A solar structure as defined in claim 7, wherein a combination of juxtapositioned materials may cover the internal space at any one time. 